In his new book, historian Niall Ferguson applies the concept of social networks to history. He asks how networks shape the spread of ideas and can help create a form of power different from that of hierarchies. In the spirit of network analysis, I will start by noting that the acknowledgments and works-cited sections demonstrate that Ferguson has clearly talked to experts in the field and read widely through the scholarly literature. I think he would appreciate it as an affirmation of his thesis that I wondered whether his time at Stanford, a university that has in many ways led the sociological study of markets, was the inspiration for this book.

The beginning of his volume provides an overview of social-network theory, but the rest is devoted to applying this theory to a reading of history, and is arranged chronologically. Applying networks to history is a challenging enterprise, given that network analysis requires extremely fine-grained data, with information not just on people but on relationships or interactions. In one of Ferguson’s original analyses, and in a fair number of cases in which he reviews the analyses of others, there are sufficient data for a formal network analysis, but just as often he uses networks as a concept in purely narrative history. The book’s main theme is that the relative importance of hierarchies (by which he mostly means states) and networks (by which he sometimes means networks and at other times means civil society) has ebbed and flowed.

Ferguson’s review of network theory goes over most of the concepts one would encounter in a college course on the subject. Two specific network concepts he discusses are especially important to the historical analysis that constitutes the bulk of the book. The first is “betweenness centrality,” a metric for identifying who in a network is most important to connecting otherwise distinct clusters within that network. The second is the notion that a hierarchy is a special type of network — one in which the network forms a branching tree with no horizontal ties. For example, imagine a military in which all communication goes through the chain of command, so that privates in a squad communicate only through their lieutenant, and lieutenants in a company only through their captain. Understanding hierarchies as a special type of network is important, as the central conceit of the book is contrasting hierarchies with (other) networks.

For the most part, Ferguson reviews network theory correctly, but he misunderstands the concept of a “big man.” In sociology and anthropology, a “big man” is generous and influential but has no formal authority. In a highly cited article, Marshall Sahlins contrasted the gregarious big men of Melanesia to the autocratic chiefs of Polynesia. Ferguson uses “big man” as if it were just technical jargon for chief or king, rather than its opposite. This confusion is significant: It suggests the need for caution about Ferguson’s inferences about the prevalence of hierarchy in periods and places outside the scope of modernity.

Ferguson is simply wrong to say that “for most of history, life has been hierarchical” and to claim that in primitive tribes someone needs to decide for the group when to perform tasks and how to allocate resources. This is basically true of agricultural city-states from Hammurabi’s Babylon to Kamehameha’s Hawaii, but you will be hard pressed to find an anthropologist who finds it consistent with the experiences of stateless hunter-gatherers. (The support Ferguson cites for this argument is a computational model from theoretical biology that makes unrealistic assumptions about the distribution of wealth in a primitive context.) Readers who are interested in understanding the roles of hierarchy and decentralized networks in pre-modern humanity would be better served by John Levi Martin’s Social Structures (2009) or Francis Fukuyama’s Origins of Political Order (2011).

Aside from a chapter tersely covering history from the Neolithic period to the 13th century, the book is devoted wholly to events from the early modern era to the present. As befits Ferguson’s expertise, he gives special, but not exclusive, emphasis to international banking and imperialism. This historical review begins with an analysis of how the Medici achieved dominance of Florence through their “high betweenness” structural position between the “new men” and “patrician” factions. Ferguson’s narrative then picks up steam with a biography of Benedetto Cotrugli, whose egocentric network he uses as a case study in the small world of Renaissance commerce. From there, he goes on to the age of exploration and shows that much of it was an ad hoc affair, based on light-footprint trading outposts in the case of the Portuguese and loose companies of adventurers in the case of the Spanish. (The conquistadors formed ties to native networks — for example, with the marriage alliances used by Pizarro.)

His analyses of the Protestant Reformation and the Enlightenment are based on letters that are extremely illuminating about the periods and that also provide general lessons about how networks function. For instance, Ferguson’s discussion of the English Reformation demonstrates how the strategic deletion of a hub (in this case, the execution of John Bradford) can make a network much more disconnected.

His chapters on the system of great-power relations that prevailed after Napoleon show how useful network analysis can be in understanding geopolitics. Through most of the book, Ferguson is interested in networks of individuals within (or occasionally across) states, but in this case the network is of relationships between states. Britain served as an offshore balancer of power for Europe (it had, basically, a “high betweenness”) and thereby helped provide stability in a multipolar system without a single hegemon. Similarly, using Emily Erickson’s work, Ferguson discusses how ship captains in the British East India Company had enough de facto autonomy to conduct intra-Asian trade, which let the EIC serve as a trade network between Asian nations. These examples of networks between states show that the conceptual tool of networks need not be limited to an opposition of networks-versus-hierarchies but can also apply to situations in which there are networks of hierarchies. (Although this is not Ferguson’s example, one can think of the Iliad, in which each king has despotic power over his subjects, but Agamemnon is only first among equals in the network of Achaean kings. That’s why he has to persuade the other kings to fight.)

In the sections of the book covering the recent past, Ferguson has a tendency to introduce topics that are interesting but only loosely connected to the conceptual lens of networks and hierarchies. For instance, the administrative state has been a critical aspect of American history since the Wilson administration, but it is not clear how it relates to either networks or hierarchy. Ferguson describes it as a return of hierarchy, but this is inconsistent with its substantial autonomy from the elected president to whom it is nominally subordinate.

Another problem is that Ferguson describes recent events as illustrating the role of networks despite evidence that networks are often dwarfed by other forces. The role of Twitter in the Arab Spring, for example, is a story too good not to tell, but even Ferguson acknowledges that television was the main source of information and connection during those events. Obviously, Al Jazeera TV could not create protests ex nihilo, but only spread news of them so they might be imitated, and this is in a meaningful sense a bottom-up process — but still, that news did spread through a satellite TV channel, not through social networks.

Similarly, Ferguson describes Brexit and the Trump campaign as network-based. They were certainly insurgent campaigns opposed by political establishments, but this does not necessarily mean that they were network-based: Both campaigns seem to have benefited at least as much from skillful political entrepreneurship of a more conventional kind. Ferguson shows that Trump had a much more prominent social-media presence than Clinton and notes that Clinton outspent Trump considerably, but he ignores that television had a huge role in Trump’s success. The TV channels were eager to provide coverage of him, which the media-tracking firm mediaQuant estimated as equivalent to almost $5 billion in advertising. Again, that Trump had fascinating and well-attended rallies that television channels found worth broadcasting gave him a great advantage, but it didn’t really have to do with networks.

Throughout the book, Ferguson oscillates between a strict definition of networks, as the aggregation of one-to-one relationships in a social system, and a looser definition that encompasses social movements and civil-society associations. For instance, he describes secret societies and fraternal lodges (e.g., the Illuminati and the Freemasons) as networks even when they have a hierarchical structure. It is certainly likely that networks exist within voluntary associations, but to treat the associations as identical to networks is like saying a human being is a circulatory system of blood.

In many places Ferguson uses “network” in the precise sense. This is true anytime he provides a network graph, but also in his fascinating discussion of the Cambridge Five ring of Communist spies. Their tight bonds with one another, formed in the Apostles honor society, are essential to understanding why they betrayed their country even after they became cynical about the Soviet Union. Similarly, their bonds to non-Communist British elites show how they remained in sensitive positions despite pasts as open Communists and suspicious behavior continuing well into the Cold War. British counterintelligence during this period seems to have been guided less by the evidence of who was a spy than by the network ties of the British elite.

In other cases, Ferguson uses “network” as little more than a homonym, as when he treats as meaningful the fact that TV channels are called “networks,” even though they are called that only as a linguistic fossil of American broadcasting’s historic network–affiliate structure. A certain amount of conceptual slippage might be a matter of indifference to the general reader or to Ferguson’s fellow historians, who may reasonably think that the historical facts and analysis are interesting regardless of how strictly they distinguish among varieties of alternatives to hierarchy.

But to this sociologist’s ear, conflating social networks, civic organizations, and social movements is confusing and imprecise. Some forms of human action are shaped by the structure of personal relationships. Others are shaped by affiliation with voluntary associations from which we derive identity and meaning. Both are important alternatives to hierarchy, but they work in different ways and so should be kept distinct.